Field of the Invention
Embodiments of the invention relate to a time-division driving type touch sensing device and a method for driving the same.
Discussion of the Related Art
User interfaces (UI) are configured so that users are able to communicate with various electronic devices and thus can easily and comfortably control the electronic devices as they desire. Examples of a user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), and a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technology has continuously expanded to increase usability and handling convenience. The user interfaces have been recently developed to include touch UI, voice recognition UI, 3D UI, etc.
The touch UI has been used in mobile devices. The touch UI is implemented by forming a touch screen on the screen of a display element. The touch screen may be implemented as a capacitive touch screen. The touch screen has capacitive touch sensors sensing changes (i.e., changes in charges of the touch sensor) in a capacitance generated when the user touches the touch sensor with his or her finger or a conductive material, and thus detects a touch input.
A touch sensing device having a touch screen integrated type display element senses changes in capacitance of touch sensors before and after a touch (or proximity) operation and decides whether or not there is a touch (or proximity) input using a conductive material. Further, the touch sensing device finds out a position of the touch input when there is the touch input. In the touch sensing device, one frame period may be time-divided into a pixel driving period P1, in which data of an input image is applied to pixels of the display element, and a touch sensor driving period P2, in which the touch sensors are driven, as shown in FIG. 1.
The time-division driving type touch sensing device has a problem of an increase in power consumption due to power consumed by circuit blocks, that are not used in the driving periods P1 and P2.
The time-division driving type touch sensing device may include a source driver integrated circuit (IC), that normally operates only during the pixel driving period P1, and a readout IC, that normally operates only during the touch sensor driving period P2. The source driver IC does not need to operate during the touch sensor driving period P2 and thus is not used during the touch sensor driving period P2. On the other hand, the readout IC does not need to operate during the pixel driving period P1 and thus is not used during the pixel driving period P1.
However, during operation of the time-division driving type touch sensing device, driving power is continuously supplied to each of the source driver IC and the readout IC. Thus, unnecessary current flows into the unused readout IC during the pixel driving period P1, and also unnecessary current flows into the unused source driver IC during the touch sensor driving period P2. Hence, the power consumption of the time-division driving type touch sensing device increases.